Heavy media separator



Jan. 13, 1959 M, MH L ETA 2,868,376

HEAVY MEDIA SEPARATOR Filed July 9, 1954 4 Sheets-Sheet 1 INVEHTORS.

George M. Meisel Harry P. Kau fz ATTORNEY 1959, G. M. MEISEL ET AL 2,353,376

HEAVY MEDIA SEPARA'l-OR Filed July 9, 1954 INYENTORS.

George M. Meise/ Harry E. Kaufz ATTORNEY Jan. 13, 1959 M. MEISEL ET AL 2,868,376

HEAVY MEDIA SEPARATOR Filed July 9, 1954 I 4 Sheets-Sheet 5 mvgmons.

George M. Meisell Harry P. Kaufz 4 TTORNE) draining the sink prior to discharge.

United States Patent Office 2,868,376 HEAVYJMEDIA SEPARATOR George M. Meisel, Denver, Colo., and Harry P. Kautz, Starke, Fla., assignors, by mesne assignments, to The Mine & Smelter Supply Co., a corporation of Colorado Application July 9, 1954, Serial No. 442,346

14 Claims. .(Cl. 209-1725) and anelevated discharge for the sink or coarse rake 'products,and a spiral conveyor for agitating the pulp and raking the sink out of the tank. Such classifiers are used forthe purpose of segregating a mass of grains of mixed sizes and/ or different specific gravities into various grades or sizes. The segregation or sorting is a hydraulic classification, or separationin media of controlled density.

In theseparation of certain ores it has been found desirableto add a pulp which has a specific gravity between the float and the sink products of the feed. The addition of this material, known asheavy media, achieves sharp separation of the density fractions of the pulp. Generally, the heavy media'stratifies in the pulp pool, and it remains substantially constant under closely controlled conditions of feed, overflow, etci Under nearly ideal conditions only very small amounts of media are required to be added, since the discharges from the pool are drained and Washed so that the media can be reclaimed and returned to thepool." i

In general, the classifiers of the present invention cornprise an Akins or spiral conveyor type mechanical separator. Such a classifier is adapted to utilize heavy media to achieve the separation of the-various density fractions of the feed. Thecrushed feed is introduced below the surface of the pool. The float overflow is generally on the side of the pool opposite the feed inlet. The sink is discharged out of the pool at the top end of the sloping bottom of the tank, generally at the same side of the pool as the feed inlet. provided between the pool and the sink discharge for There is, also, provided a discharge for middling, which is a density fraction between the float and the sink, The middling discharge is adjustable to discharge middling from various points vertically across orhorizontally alongthe pool to accommodate the varying middling strata from different ores, different media, etc. The horizontally or vertically variable discharge is provided as an outlet for the middling, to permit the discharge of middling from any of the various'density strata in the pool. This feature is especially valuable, as each ore pulp and/ or heavy media creates strata of varying depth, position, etc. in the tank. The middling is discharged into a launder box which may provide means for discharging middling from a stratum below thesurface of the pool.

To reduce the amount of media required for the discharge to float and/or middling, a mechanical skimmer is provided adjacent the float and/or middling overflow to draw the two products into the respective launders over the weir type overflows. A constant head tank for the heavy media supplies the media both into the feed inlet and into'the middling area. Feeding the heavy media into both points of the pool assures maintenance A dry deck may be 2,868,376 Patented Jan. 13, 1959 of sufficiently high specific gravity in the middling area to separate and discharge a product of somewhat high specific gravity. Therefore, while fine feed is being fed into the deeper part of the pool, screened out coarse feed requiring for its separation a pool of comparatively higher specific gravity may be fed simultaneously into a shallower part of the pool of the same vessel. A feed baffle forces the feed below the surface of the pool, pre venting it from streaking across the pool surface and forcing it into the depth of the pool, achieving the separation of the density fractions in the travel. A float barrier between the float outlet and the middling outlets retains the float product within a float compartment. The float barrier may be a partition or a stream of. heavy media there introduced. The skimmer reduces the amount of heavy media requiredto overflow the floatand/or middling product and thus reduces the circulating load of heavy media.

It is an object of the present inventiontto provide a classifier in which various density fractions of the feed are separated, including a heavy or sink fraction, a middling fraction, and a light or float fraction. i

Another object of the invention is to provide classifying apparatus which is readily adjustable to the beneficiation of various ores, minerals, etc. A further object of the present invention is to provide classifying apparatus which is adapted to useheavy media to achieve a sharp separation of the various density fractions of the feed.

A further object of the present invention is to provide classifying apparatus with a pool of ditferentialjdensity adapted to segregate float and middling fractions of differential specific gravity, also permitting simultaneous separation of fine and coarse feed within the samevessel.

Still another object of the present invention is to provide classifying apparatus adapted to provide a con,- stant heavy media flow in the pulp pool to achieve separation of the pulp fractions.

' These and otherobjects and advantages of the present invention will be readilyapparent by referring to the following description and appended drawings, in which:

Fig; l is aside elevation of a classifier according to the present invention;

Fig. 2 is a sectional view of the screw conveyor and tank of the classifier illustrated in Fig. 1, taken along section line 2-2; i Fig. 3 is a sectional view showing an alternate ar rangement'used for vertically adjustable middling ports; Fig. 4 is a top planview of the conveyor of Fig. 1;

Fig. 5 is an end elevation of the device of Fig. 1;

Fig. 6 is a section taken along line 6-6 of Fig. 3 showing a vertically adjustable mids discharge;

Fig. 7 is a modified middling discharge; and

Fig. 8 is another modified middling discharge.

In the device selected for illustration, :a tank 10, having a roundedbottom 12 is adapted to operate at 'an angle to the pool line. In this position the tank will hold a pool of orefland heavy media for segregating into the various density components. A spiral conveyor 14, rotated by gear drive means 16, is generally offset with regard to the center line of the tank to protect the tank side with a cushion of raked sink material. The conveyor is offset to. provide for a cushion as largeor larger than the maximum size of raked sink material. Power elevating means, shown by the general index number 18, raises and lowers the conveyor as desired. A generally rectangular or triangularweir 20 is provided at the deep end of the pool along the pool level, to discharge float from the surface of the pool. The discharge may be any convenient shape and size to provide sufficient capacity for the float product. Mechanical Skimmers 22 are juxtaposed above the weirs on a rotatable shaft 24. The

skimmers are rotated by means of a drive 26, and as they rotate they place the float over the weirs into a float launder 28. The float is discharged from the launder by means of the float launder opening 29. A sink discharge is provided above the pool level at the top of the sloping bottom 12. By adjusting the pool level, a portion of the bottom 12 adjacent the discharge 30 may be above the pool level to provide a dry deck for draining the rake products. A feed inlet 32 is provided on the tank generally on the side opposite the float outlet. A feed baflle 31 directs the pulp feed from the inlet 32 below the surface of the pool preventing it from streaking across the pool surface. The feed may also be introduced similarly at the tank end by means of a feed chest 32a. Taking advantage of the prevailing specific gravity diiferential within the pool, a secondary feed inlet 3212 may be added in the shallower part of the pool, allowing screened out coarse material to be fed separately from the fines fed through feed inlet 32. Along the tank side, opposite the pulp feed 32, a series of openings 33 are disposed between the float and the sink discharge outlets vertically across, or horizontally along the pool level. The openings 33 are adapted to be raised or lowered, partially or totally opened and closed by weir slats or sliding doors, to permit opening a discharge to a se lected point on the tank for the discharge of middling. With the selector trays in Fig. 2 in the dotted up 66 position, high specific gravity middling discharges into middling launder 34. The middling, or mids is discharged from the launder by means of the middling launder openings 35. With the selector trays in Fig. 2 in the down 67 position, middling of low specific gravity and/or coarse float can be discharged into the float launder 28 and blended with the float product from the weir 20. As an alternate, as shown in Figs. 3 and 6, the middling is discharged into a launder box 56 immediately adjacent the tank 10 and connected therewith by means of a passage 33. A movable skimmer 22w may be provided on an overflow weir 55 for discharging the middling from the launder box. The middling is discharged into middling launder 34 adjacent thereto. Each of the discharge doors comprises a door plate 54 having an opening 53 therethrough which comprises less than half the door plate. The plates 54 are moved vertically by manual, hydraulic or mechanical means 52 to locate and control the size of the door opening. An opening 53 in the wall of the tank is adapted to be covered by the solid portion 52 of the sliding gate, and is adapted to be opened from partially open to full open by means of the plate 54. Various strata of the pool are indicated by dotted lines 50 which show, in general, the configuration of strata along the pool. These strata, obviously, will change with diiferent ores and with different heavy media. The discharge ports are provided along the pool, opening to different depths so that any of the various strata may be discharged from the pool. In Fig. 6, illustrating a discharge scheme in one instance, the pair of discharge ports 33 are opened sufliciently to take maximum discharge benefits of a stratum 50 which cuts across both the discharge ports. As any strata to be discharged changes across the various openings, the doors may be opened varying amounts either together or singly for the discharge of the stratum which passes across the discharge openings.

In Fig. 7 a modified middling discharge port is provided, comprising a slidable plate 54 having an opening 53 intermediate the ends thereof. The plate 54 substantially closes an opening 33 in the tank wall which extends downwardly adjacent the bottom 12 of the tank. The plate is vertically slidable so that the discharge port 53 is raised and lowered to accommodate any of the strata of the pool desired to be discharged. For example, the position indicated would discharge a stratum 50 into the middling launder box 56. The discharge will be available to discharge any of the strata of the pool, by sliding the plate to the desired position.

The modified discharge of Fig. 8 is similar to that of Fig. 7, except that a series of slats, or plate 54 having a relatively small opening therein, is utilized to substantially close the tank opening 33. The small opening is valuable where the range of specific gravity of the desired middling stratum is narrow and a very sharp separation is desired. This may be further modified by varying the size of the opening and/or the general shape thereof. A drain 36 at the bottom of the pool is provided to completely empty the tank, in the event a shut down is desired.

A float barrier 38, adjustably suspended by a yoke 39, and held on cable drums 41 operated by the spiral lift 18, is adapted to be lowered into the surface of the pool to keep the float from progressing up the pool surface into the exposed conveyor and into the middling or' the sink outlets. The float barrier is interconnected to the spiral lift so it will not interfere with the raising of the spiral. The skimmers keep the float from building up on the surface of the float compartment and/or the middling launder box, and help reduce the circulating load of heavy media required to discharge float and/or middling over the weirs.

The heavy media is fed into the pool through inlet 4%) in the pulp feed 32 and inlet 42 at the pool surface in the middlings section. The latter assures maintenance of sufliciently high specific gravity in the mids zone to separate and discharge products of relatively high specific gravity. A valve 44 is provided to adjust the rate of heavy media going into the feed. A conical or pyramidal tank 46 supplies heavy media at a constant head into the two areas. The constant head tank is fed through an inlet 48 from a heavy media makeup station.

In operation, crushed feed is fed into the feed chest 32 generally on the side of the classifier. The tank is filled to the desired level, forming a pulp pool. Settletable solids or sink settle to the bottom of the tank and are picked up by the slow moving conveyor and advanced up the sloping bottom toward the sink discharge. The heavy media, which is a pulp having a specific gravity between the float and the sink of the core is introduced into the pool through both ports 40 and 42. The feed from the inlet 32 is directed by the feed baflle 31 substantially below the surface of the pool. As the heavy media stratifies in the pool, generally intermediate the surface and the bottom thereof, the feed must pass through the more dense heavy media. This action achieves the separation of the density fractions of the feed. The particles of low specific gravity rise to the surface of the pool and float thereon. The float barrier 38 is lowered to the surface of the pool to confine the float within the float overflow area. The float is discharged over the weir 20, and is aided in discharge by means of the skimmers 22 which pull the float across the weirs and into the launder.

The settleable matteror sink falls to the bottom of the pool and is picked up by the screw conveyor and advances toward the discharge 30. In Fig. 2, it is generally shown that with clockwise rotation of the conveyor the sink tends to pile up along the left Wall of the tank. With the conveyor somewhat offset, as shown, it provides its own cushion of sink material against the tank sides, protecting the latter from dimpling by material caught between the spiral and the tank side. Mids discharge openings are provided along the righthand wall opposite the sink, so that the sink is not discharged out of the middling discharges. The middling stratifies above the sink and at least one of the middling discharge openings will be in a position to discharge middling and not the sink. The" point of discharge of the middling fraction varies from ore to ore and also with a change of heavy media. Under ideal conditions, which obviously cannot be obtained, the heavy media would be a constant unmoving layer, which is not discharged from the pool. However, under normal, operation some of the heavy media is discharged with allthree fractions, and means must be provided for supplying media to keep the flow constant. A constant head feed supply 46 is utilized to supply heavy media both into the pulp feed and in the middlings area. Generally, the heavy media stratifies into curved contours, such as shown by the dotted line 50 in Fig. 1. The middling strata generally follow the heavy media contours and the middling opening nearest the respective middling stratum would be utilized to discharge the desired middling fraction. The middling stratum will change with ore, conveyor speed, etc., and the dotted line 50 shows only one of several configurations such a layer may assume. One of the various middling discharge outlets along the pool surface will coincide with the desired stratumfor discharge. a

The discharge orifice shown in Fig. 7 is adapted to be vertically raised and lowered along the tank side so that any fraction can be withdrawn from the pool. Likewise, the orifice of Fig. 8 may be vertically raised or lowered to similarly withdraw a particular stratum of the pool. In general, these doors are used in conjunction with a series of outlets such as indicatedat 33; however, under certain operatingconditions, one vertically movable orifice may be sufficientfor the discharge of the middling fractions of a particular ore, not including, of course, the float and the sink from the pool.

In certain operations, such as classifying coal froma mine, the middling is a main product used to blend with the floatto achieve the desired ash content. To obtain a sharp separation heavy media are introduced into the pool. 1 In this case it is generally desirable to have a coal of a very narrow range of ash content as the end product, so that the device of the present invention is especially valuable in withdrawing the middling fraction from a particular stratum in the pool. By withdrawing middling from a fraction beneath the surface of the pool, the same close density control maybe obtained, as by withdrawing such a fraction from the surface. n V

The description and appended drawings are intended for illustration only, and it ,is not intended to limit the invention to the details so disclosed, except insofar as defined by the appended claims." I

We claim:

l. Classification apparatii slfo r separating density fractions of a pulp comprising a tank adapted to hold a pool of pulp, a screw conveyor in said .tank extending beyond said pool, ,a float overflow for said pool, a sink discharge on said tank above the level'of said pool, said conveyor adapted to carry sink from said pool to said sink discharge, and outlet means for discharging middling from a predetermined strata in said pool, said middling dischargerneans including openings along the side of said tank intermediate said float overflow and said sink dischargeand displaceablesubstantially between the tank bottom and the pool surface, and means for discharging middling into a launder box remote from said tank.

2. Classificationapparatus for separating density fractions of a pulp comprising a tank adapted 'to hold a pool of pulp, a screw conveyor. ofiset with respect to the con terline of said tank extending beyond said pool, a float overflow for saidpool, "asink discharge on said tank above ,the level of said pool, said conveyor adapted to carry sink from said p001 tosaid discharge, plural outlet means on a tank wall adjacent. said float overflow for the discharge of middling, said plural outlet means adapted to discharge middlin'g from predetermined strata of said pool, means for blending themiddling withlthe float, skimmer means associated'with said float outlet whereby float adjacent said outlet is discharged from said pool, skimmer means associated with middling outlets for discharge of middling, .and a feed inlet below the pool surface.

3. Classification apparatus for separating density fractions of a pulp comprising a tank adapted to hold a pool of pulp, a screw conveyor offset from the centerline of said tank extending out of said pool, a float overflow for said pool, a sink discharge on said tank above the level is discharged from said pool, means for blending the middling and the float product, and a feed submerged by a baffle below the surface of the pool.

4. Classification apparatus for separating slurry into plural density fractions comprising a tank for holding a pool of pulp, a screw conveyor for removing settled sink from said pool, means beyond said pool for discharging said sink from said tank, discharge means associated with the surface of said pool for discharging float therefrom, plural means mounted on a tank, wall along the pool surface for discharging middling from predetermined strata of said pool, means for blending the middling and float products, means circulating heavy media into the feed and said middling zones of. said pool at aconstant head thereby to achieve the separation and discharge of float and middling from fractions of said pulp, and feed means below the pool surface.

5. Classification apparatus for separating plural density fractions ofa pulp, comprisinga tank for holding a pool of pulp, said tank having a sloping bottom extending beyond the pool level, feed means for screened-out fines on said tank adjacent the deep end thereof, float outlet means on said tank adjacent the deep end of said pool remote from said feed inlet, an offset spiral conveyor in said tank adapted to withdraw 'settledsink from said pool, sink discharge means associated with said conveyor remote from saidpool, secondary feed inlet means intermediatethe ends of said tank for introducing screenedout coarse, discharge means for fine and coarse float and middling inclusive of at least one skimmer to aid such discharge, and means for feeding heavy media into the fine and the coarse float and middling areas to achieve separation and discharge of both float and middling fractions at different specific gravities;

6. Classification apparatus for separating plural density fractions of a pulp comprising a tank for holding a pool of pulp, said tank having upright sides and a sloping bottom extending beyond the pool level, feed means on the side of said tankadjacent thedeep end thereof, said feed inlet including'means for directing said feed below the pool surface, float outlet means on said tank opposite said inlet, an offset spiral conveyor in'said tank adapted to withdraw settled sink from said pool, sink discharge means associated with said conveyor away from said pool, outlet means intermediate the ends of said tank for discharging middling, rneans inclusiveof skimmer means for discharging said float and said middling through said float and middling outlets respectively, andrneans for feeding heavy media into the feed and the middling area to achieve separation and discharge of the float and middling fractions of differential specific gravity.

7. Classification apparatus for separating plural density fractions of a pulp comprising a tank for holding a pool of pulp, said tank having upright sides and a sloping bottom extending beyond the pool level, feed means on said tank adjacent one end thereof, said feed including means to direct said feed below the pool surface, float outlet meanson said tankremote from said inlet and adjacent the deep endof said pool, barrier means adapted to confine said float in a float area, a spiral conveyor in said tank adapted to withdraw settled sink from said pool, sink discharge means associated with said conveyor remote from said pool, outlet means intermediate the ends of said tank for discharging middling, said float area being separated from the middling outlet, skimmer means for individually discharging float and middling, and means for feeding heavy media into the feed and the middling area to achieve separation and discharge of float and middling fractions of differential specific gravity.

8. Classification apparatus for separating plural density fractions of a pulp comprising a tank for holding a pool of pulp, said tank having a sloping bottom exending beyond the pool level, feed means for screened-out fines on the side of said tank adjacent the deep end thereof, said fines feed including means for directing said feed below the pool surface, float outlet means for screenedout fines on said tank opposite said inlet, barrier means adapted to confine said fine float between the feed inlet and the float outlet means, an offset spiral conveyor in said tank adapted to withdraw settled sink from said pool, sink discharge means associated with said conveyor remote from said pool, secondary feed means beyond said barrier means for introducing screened-out coarse, outlet means along the surface of said pool intermediate the ends thereof for separating and discharging screened-out coarse and middling, means associated with said float and middling outlets to discharge float and middling respectively through said outlets, and means for feeding heavy media into' the fine and coarse float and middling areas to achieve separation and discharge of both float and middling fractions of dilferential specific gravity.

9. Classification apparatus for separating plural density fractions of a pulp comprising a tank for holding a pool of pulp, said tank having upright sides and a sloping bottom extending beyond the pool level, feed means on the side of said tank adjacent the deep end thereof, said feed including means to direct said feed below the pool surface, float outlet means on said tank opposite said inlet, barrier means adapted to confine said float in an area adjacent said float outlet means, an offset spiral conveyor in said tank adapted to withdraw settled sink from said pool, sink discharge means associated with said conveyor remote from said pool, variable outlet means along the tank side adjacent said float outlet adapted to discharge predetermined middling strata, and said float area being remote from said feed means and remote from said middling outlets, means inclusive of rotating paddle skimmers to aid the discharge of float and middling from their respective outlets, means for feeding heavy media at a constant head into the feed and the middling discharge areas to achieve separation of the various fractions.

10. In a screw classifier, a tank adapted to hold a pool of pulp, feed means for said pool, means for discharging middling from predetermined strata in said pool, said 'middling discharging into a launder box remote from said tank, said middling discharge means including openings along the side of said tank displaceable between the tank bottom and the pool level, and means for discharging the middling from said launder box.

11. In a screw classifier, a tank adapted to hold a pool of pulp, feed means for said pool, means for discharging middling from predetermined strata in said pool, said middling discharging into a launder box remote from said tank, said middling discharge means including variable rectangular openings displaceable along the side of said tank between the tank bottom and the pool level, and means for discharging the middling from said launder box.

12. In apparatus for heavy media separations, a tank for pulp having upright sides and a sloping bottom defining a pool of substantial extent lengthwise of the tank and having separate overflows for float and middlings products along a side of said pool, an offset screw conveyor means for moving sink product along the sloping bottom through the pool to an elevated point of discharge above said pool partitioning means disposed transversely of the pool with its top surface above the liquid level and its lower surface below said level and spaced from the top surface of the screw conveyor means so as to divide the pool into a plurality of separation zones, and means along the tank side adjacent the deep end of said pool for feeding material below the pool surface to be separated into a float separation zone of the pool, said float overflow being along the tank side opposite said feed means, said partitioning meansconfining the float content of the feed to the float separation Zone for its direct removal from the tank across the float overflow, while permitting sink and middlings to pass from said zone by submergence for separation and overflow from their adjoining treatment zone. I

13. In apparatus for heavy media separations, a tank for pulp having upright sides and a sloping bottom defining a pool of substantial extent lengthwise of the tank and having separate overflows for float and middlings products along a side of said pool, an offset screw conveyor means for moving sink product along the sloping bottom through the pool to an elevated point of discharge above said pool, partitioning means disposed transversely of the pool with its top surface above the liquid level and its lower surface below said level and spaced from the top surface of the screw conveyor means so as to divide the pool into a plurality of separation zones, and means on the tank and adjacent the deep end of the pool for feeding material below the pool surface to be separated into a float separation zone of the pool, said float overflow being along the tank side adjacent the deep end of said pool, said partitioning means confining the float content of the feed to the float separation zone for its direct removal from the tank across the float overflow, while permitting sink and middlings to pass from said zone -by submergence for separation and overflow from their adjoining treatment zone. I

14. In apparatus for heavy media separations, a tank for pulp having upright sidesand a sloping bottom defining a pool of substantial extent lengthwise of the tank and having separate overflows for float and middlings products along a side of said pool, an offset screw conveyor means for moving sink product along the sloping bottom through the pool to an elevated point of discharge above said pool, barrier means disposed transversely of the pool so as to divide the pool into a plurality of separation zones, and means for feeding material to be separated into a float separation zone below the surface of the pool, said barrier means confining the float content of the feed to the float separation zone for its direct removal from the tank across the float overflow, while permitting sink and middlings to pass from said zone by submergence for separation and overflow from their adjoining treatment zone.

References Cited in the file of this patent UNITED STATES PATENTS 1,556,676 Chance Oct. 13, 1925 1,866,005 Beatty July 5, 1932 2,468,005 Walker et al. Apr. 19, 1949 2,621,791 Bitzer Dec. 16, 1952 2,701,058 Leeman Feb. 1, 1955 FOREIGN PATENTS 371,394 Germany Mar. 15, 1923 709,980 Great Britain June 2, 1954 

